The overall objective of this proposal is to establish and maintain at the University of Chicago an environment in which multidisciplinary research in various biomedical aspects of the population problem can expand and flourish. The Center, with its core facilities and lines of communication, enhances the efficiency and output of the many population-related research projects underway at this University, encourages the inception of new endeavors and provides a framework and stimulus for additional collaborative research programs among investigators of different disciplines and backgrounds. The Center involves 34 scientists with primary appointments in eight Departments of the Division of Biological Sciences, some of whom hold joint appointments involving five other Departments. Research projects and collaborative programs now in progress cover a broad spectrum of important areas, including laboratory and clinical investigations of ovarian, testicular and placental function, control of fertility and infertility, sperm and ovum biology, gamete transport, fertilization and meiosis, sex hormone, prostaglandin and polyamine action, population genetics, cytogenetics, amniocentesis and genetic counselling, sexual behavior and family planning. Instruction and training endeavors include a monthly seminar series, drawing half the speakers from outside the University, and a multi-disciplinary course in population biology, for credit to graduate and advanced undergraduate students.